GPA

港控/mmm° 2023-07-17 04:59 82阅读 0赞

## Problem Description ##

Each course grade is one of the following five letters: A, B, C, D, and F. (Note that there is no grade E.) The grade A indicates superior achievement , whereas F stands for failure. In order to calculate the GPA, the letter grades A, B, C, D, and F are assigned the following grade points, respectively: 4, 3, 2, 1, and 0.  
**Input**  
The input file will contain data for one or more test cases, one test case per line. On each line there will be one or more upper case letters, separated by blank spaces.  
**Output**  
Each line of input will result in exactly one line of output. If all upper case letters on a particular line of input came from the set \{A, B, C, D, F\} then the output will consist of the GPA, displayed with a precision of two decimal places. Otherwise, the message “Unknown letter grade in input” will be printed.

**Sample Input**

B C D F
    B F F C C A
    D C E F

**Sample Output**

2.00
    1.83
    Unknown letter grade in input

**Code:**  
思路：利用switch case 语句对输入的等级进行判断并计算;注意在while（cin>>c）循环中如何退出循环\[利用getchar()函数\]；注意除法运算时，分母不为0，否则会抛出异常

#include<iostream>
    #include<iomanip>
    using namespace std;
    int main() {
        
    	char c,ch;
    	float sum;
    	int count,point;
    	float gpa;
    	bool flag;
    	while (1) {
        
    		flag = true; sum = 0; count = 0; point = 0;
    		while (cin >> c) {
        
    			switch (c) {
        
    			case'A':point = 4; count++; break;
    			case'B':point = 3; count++; break;
    			case'C':point = 2; count++; break;
    			case'D':point = 1; count++; break;
    			case'F':point = 0; count++; break;
    			default:flag = false; break;
    			}
    			sum = sum + point;
    			if ((ch = getchar()) == '\n') break;
    		}
    		if (flag == false) {
        
    			cout << "Unknown letter grade in input" << endl;
    		}
    		else if (count == 0) {
        
    			return 0;
    		}
    		else{
        
    			gpa = sum / count;
    			cout << setiosflags(ios::fixed);
    			cout << setprecision(2) << gpa << endl;
    		}
    	}
    }